With recent advances in the sophistication of the image sensors with which image capturing apparatuses such as digital still cameras and the like are equipped, performing high-speed, high-accuracy image processing has become more important than ever. At the same time, conventionally, a method of performing autofocus (hereinafter “focus detection”) quickly and accurately using a portion of the area of the image sensor for focus adjustment has been proposed.
Japanese Patent Laid-Open No. 2000-156823 discloses an image capturing apparatus in which divided-pupil pixels used for focus detection (hereinafter “focus detection pixels”) are positioned at a portion of the G color filters of the R, G, B color filters of the image sensor. Focus detection is performed based on information obtained from these focus detection pixels. Although pixel signals for focus detection are obtained from the focus detection pixels, pixel signals for forming part of an image are not obtained. As a result, it is necessary to compensate signals from the focus detection pixels with neighboring pixel signals of image forming pixels for which pixel signals for forming part of an image are obtained.
By contrast, Japanese Patent Laid-Open No. 2000-305010 discloses a method of interpolating image signals for forming images lost at the positions of the focus detection pixels using image signals obtained from pixels around the focus detection pixels. However, in a case in which defects in the manufacturing process of the image sensor such as white defects and black defects are present in the focus detection pixels, it is difficult to correct the pixel signals for focus detection obtained from the focus detection pixels using the image signals of pixels around the focus detection pixels.
Additionally, Japanese Patent Laid-Open No. 2001-177756 discloses performing focus detection in the same way as a case in which there is no defect in the focus detection pixels by using image forming pixels in the vicinity of the focus detection pixels as focus detection pixels when there is a defect in the focus detection pixels.
However, in Japanese Patent Laid-Open No. 2001-177756 it is assumed that the focus detection pixels are not configured as divided-pupil pixels and are configured the same way as the image forming pixels. As a result, in a case in which the focus detection pixels are configured as divided-pupil pixels, when there is a defect in the focus detection pixels it is difficult to correct the image signals for focus detection using nearby image forming pixels.